The bulk motions in the Galactocentric radial and vertical directions and their variations with respect to the vertical height above and below the plane have been studied using different tracers. Within the disk, there is evidence of a wobbly radial velocity (\(V_R\) ) along the distance to the plane. Investigating velocity profiles for F-type stars sampled from the LAMOST data ([1]}; [2]}; [3]}) within Galactocentric radii \(7.8<R<9.8\,\mathrm {kpc}\)  and \(\pm 2\,\mathrm {kpc}\)  from the plane, [4]} detected a negative mean radial velocity near the plane, corresponding to an inward radial flow. They also found that the mean of \(V_R\)  increases with the increasing of \(|Z|\) . Based on RAVE ([5]}; [6]}) red-clump stars at \(|Z|<2\,\mathrm {kpc}\)  and \(6<R<10\,\mathrm {kpc}\) , [7]} found an outflow with \(V_R=8-10\,\mathrm {km\,s}^{-1}\)  for \(0<Z<1\,\mathrm {kpc}\)  and an inward motion with \(V_R=-10\,\mathrm {km\,s}^{-1}\)  at \(R=9\,\mathrm {kpc}\)  and \(-1<Z<-0.5\,\mathrm {kpc}\) . [8]} presented an analysis of kinematics of K giant stars selected from the LAMOST catalog within \(|Z|<2\,\mathrm {kpc}\)  and found that the \(V_R\)  above the plane is higher than that below the plane at \(R\sim 10-11\,\mathrm {kpc}\) . Similar north-south asymmetries in \(V_R\)  in the outer disk were also detected by [9]} and [10]} based on the LAMOST red clump stars. Sampling Gaia-LAMOST AFGK dwarf stars restricted to 1 kpc from the Sun, [11]} found a \(V_R\)  profile with a gradient \(dV_R/dZ\sim 29\,\mathrm {km\,s^{-1}\,kpc^{-1}}\)  across the plane.
